Control apparatus for internal-combustion engines



Patented Jan. 3, 1950 CONTROL APPARATUS FOR INTERNAL- COMBUSTION ENGINES Scott F. Hunt, Meriden, Conn., assigner, by mesne assignments, to Niles-Bement-Pond Company, West Hartford, Conn., a corporation of New Jersey Application October 20, 1943, Serial No. 506,945

30 Claims. (Cl. 12S- 117) The present invention relates to control apparatus for internal combustion engines, and especially to apparatus for controlling the ignition timing and the ratio of fuel to air supplied for purposes of combustion.

It has been found that internal combustion engines of the type used on aircraft may be operated at certain intermediate loads with a very lean ratio of fuel to air, which at other loads would cause faulty operation or might even result in damage to the engine. Furthermore, it has been found that the performance of the engine is improved when such a lean fuel to air ratio is used if the ignition timing is considerably advanced from its normal relationship.

The use of such an extremely lean fuel to air ratio is usually not desirable under normal conditions of engine operation, since the engine tends to run too hot, and may be damaged if the very lean mixture is used for a long period of time. Under emergency conditions, however, as when an aircraft is too far from its base to return if the fuel remaining is consumed at the normal rate, it becomes very desirable to take advantage of the economy made possible by operating on a very lean fuel to air ratio, even though the engine may be damaged as a result.

An object of the present invention is therefore to provide improved apparatus for controlling the fuel to air ratio in internal combustion engines so as to secure maximum economy.

Another object is to provide improved means whereby the pilot of an aircraft may determine whether the engine is to be operated in a conventional manner or is to operate with a fuel to air ratio and ignition timing chosen for maximum economy. f

Another object of the present invention is to provide a fuel supply system for an internal combustion engine including means'for controlling the fuel to air ratio so that a very lean ratio is provided at an intermediate range of engine loads and a richer ratio is provided when the load is outside that range.

Another object is to provide, in connection with such a system, means for advancing the ignition timing when the very lean fuel to air ratio is used.

Another object of my invention is to provide improved ignition timing and mixture control means of the type described and claimed in the copending application of Milton E. Chandler, Serial No. 491,442, filed June 19 1943, now Patent No. 3,432,283, issued December 9,1947;

A further objectY of the present invention is to provide a valve responsive to the load of the internal combustion engine for increasing the fuel toair ratio when the load exceeds a predetermined Value, and mechanical means for positively opening the valve in response to other conditions indicative of the need for a richer fuel to air ratio.

A further object is to provide, in a fuel supply system for an internal combustion engine, improved means for enriching the fuel to air ratio at low and high engine loads including a single valve responsive to the engine load, and operated so as to close when the load is in an intermediate range and open when the load is below or above that range.

A further object is to provide, in an ignition timing and mixture control system for an internal combustion engine, motor means utilizing the fuel pressure as a source of power for operating the ignition timing control.

Other objects and advantages of my invention will become apparent from a consideration of the appended specification, claims and drawing, in which Figure 1 is a somewhat diagrammatic illustration of a carburetor for an internal combustion engine, embodying an improved mixture Vcontrol system built n accordance with the principles of my invention,

Figure 2 illustrates an ignition control system built in accordance with the principles of my invention, which may be used in conjunction with the carburetor of Figure 1.

Figure 3 is a graphical illustration of the relationship betweenl the fuel to air ratio and the air flow in the carburetor of Figure 1,

Figure 4 illustrates a modied form of mixture control, which may be used in place of the mixture control arrangement of Figure 1, and

Figure 5 illustrates a modied form of mixture and ignition control, which may be used to replace the mixture control of Figure 1 and the ignition control of Figure 2.

Figure 1 valve 28. K. l M

mounted in the chamber 21. The bellows 30 is and 55 into four expansible chambers 5I, 24, 2l and 56. The diaphragms 53, 54 and 55 are attached at their centers to a sleeve valve 51, which cooperates with a conical seat 58 on a cylindrical post 88 extending thru the sleeve valve 51. The

Y right end of the post 85, as it appears in the drawin the pressurermeter 22, a conduit 25, past a" valve 26 into a chamber 21, and thr'u al conduit 28 to the throat of venturi I2.`

In the second passage just traced, there are two restrictions, the xed restriction 23: 'andy they Y Valve 26 is operated bya bellows 30 sealed, and is preferably filled with a temperature responsive uid, for example, nitrogen. Since the bellows 38 is mounted in chamber 21, it expands and contracts in accordance with the variation of the pressure and temperature in that chamber. The pressure in chamber 21 varieswith the atmospheric pressure and also with the variationsfin the velocity of the air flowing thru the Venturi restriction I2. Y

i. The difference in pressure between the inlet .Illjiahdthethroatof Venturi I2 Varies in accordance with the Velocity of the airpas'sing thruit, rather thanin accordance with the 'mass of the air'. Since, for a given mass of air flowing thru fthe, venturi, the velocity ofthe air varies. in accordance with itsA density, it will be apparent thati'inforderto secure an accurate measure of themass. of the flowing air the pressure differ- 'encei' between the inlet II and the throat of venturi I2 must be compensatedffor variations iniair; density before transmission to the pres- Vsure'meter 22. This compensation is accompli'shed by valve 28. The total pressure difference :between inlet VII andthe throat of venturi I2 may be separated into two components, one being thepressure drop acrossrestrictionr2-3 and `the other beingthe drop across valve 25. The Adropacross valve 26' is varied in accordance with the density of the flowing air in a manner so that theidropacross restriction 23 is a true measure ofthe mass. ofthe air, and is unaffected by its density.Y Y Y ISince the pressure in chamber 21 also Varies in accordance with the velocity of the air Yflowing thru Venturi restriction I2, the bellows also'loperates the valve 26l as a function offthat velocity., and'v thereby compensates for errors in herent in the characteristics of the Venturi meter.v Y y The fuel. flowing thru the carburetor comes from a fuel pumpor other source of fuel under pressure (not shown), and'passes thru a conduit 3|, 'a fuelregulator 32, a conduit 33, a mixture conf 'trol generally indicated at 34, conduits 35 and 36, a j et system generally indicated at 31, a conduit-38, pastanidle Valve 88, and through a conduit 39, a pressure regulator 48 and a conduit 4I to discharge noZzle'MI5. Y

TheV fuel regulator- 32A includes a casing 42 di- Vvided by a flexible diaphragm 43 into a pair `of expansible chambers` 44 and 45.' The diaphragm 4'3A` carries at its center a valve 46, which is balancedl against inlet pressure and biased to-v wardi open position by a spring l41. A restricted passage 48A interconnects the chambers 44 and 45. A conduit 50 connects the chamber 44 with aniexpansible chamber 5I in the pressure meter `The pressure. meterJ22 includes a housing 52 separated by three flexible diaphrag'msi Y5'3, 54

ing, carries a stop 8| to limit the movement of the valve 51 in that direction.

The mixture control 34 includes a disc valve B2 fixed onra rotatable shaft 63. The disc valve 62 may be operated by rotation of shaft 63 to selectively open and close ports connected to the conduits- 33, Y35 and 36. Rotation of shaft 63l is preferablyaccomplished by means of a manual lever or other manually operable control device.

Fuel entering the jet system 31 thru conduit 35 may flow to the conduit 38 either thru a fixed restriction 84 or thru one of a pair of variable restrictions 65 and 65. The variable restrictions Gli-and. 66 are controlled by poppet valves. 61 and 68, respectively, which are Ybiased to closed posi`- tionby-biasing spring and 1I, respectively.

Thelupper end 'of'. the steinl of.' valve 58l abuts against a rod 12 whichextends-thru a sealing diaphragm 13 to the exterior of the jet system 31 andi carriesat itsouter-end a plate 154. A cam 15- is vpositionedadjacentthe Vplate'fi and is operated by the shaftr83 of mixture` control 34. The cam 15 is so contcuredthatupon rotationof shaft 63 Yin a clockwise direction from the posi'- tion shown in the drawing, the valve 88A is positively moved' to open positionl against Vthe action ofA the biasing springll. f

Another cam 16 ispositione'd adjacent the plate 114: and .is arranged to be.' rotated concurrently withV the operation ofthrottle I4. The cam 16 is so contoured that when the throttle is in a 'range of positions,fcommcnly known as the idle range, extending from its fully closed position toa 'position approximately 20% open, the cam 1'6A engages plate 14. and operates valve 6B to open position against the action of biasing spring 1I.

Fuel entering the-:jetsystem 31` thru conduit `3Il passes thru a fixed restriction. 'Eiland 'affixed restriction 18fftothe conduit 38. diFuel flowing thru the variable restrictions @5i and 88v also passes-thru the fixed restriction 18'.

The pressure regulator Illv includes a casing 80 divided. by a flexible diaphragm 8| into a pair of expansible Vchambers 82 VVand '835. The diaphragrnV 8| carriesatits center a valve 813-,Y which is` illustratedr as being balanced against outlet pressure, andi is biased toward closed position by. aspiring 85. The chamber 82" is vented thru a conduit 86 to the passage I8 andthehcethru impact tubes I1 to the inlet` Ii.. The chamber 83 of' thepressure regulator .48 `is connected thru a conduit 8-1' to the chamber 58- ofpressure meter 22. Y f

The idle valve 88,10cated in aY casing 89, isrrarvraiigdwto reciprocate upon rctationJ of an arm 90 xed on a shaft 9|.-'Sl-iaft lll'- carries,voutside casing'- 89, another arm. 98 which is Vconnected by aflihkj91- tov anarmV 518i fixed on Vthe shaft |05 of throttle I4. The'idlevalve 'operatestorestrict the ow of fuel thru conduit 38 when the throttle I4 is in theidle range.

Operationjof Figure 1 y A'portion of the fuel ent'eringthe fuel regulator 32j passes thru restrictedAv passage 48,v chamber 4 4, conduitj-l-chamberl 5|,"pastl valve 51 to charribarl 56', an'dthru` conduit-81 to chamber 83 in the pressure regulator 40. The quantity of fuel fiowing in this manner is controlled by the position of valve 51 in the pressure meter 22. The pressure in chamber 56 of pressure meter 22 is the same as that in chamber 83 of pressure regulator 40, and hence is substantially the same as that existing on the downstream side of the jet system 31. The pressure in chamber of the pressure meter 22 is the same as that in chamber 44 of fuel regulator 32, which diners from the pressure in chamber 45 by an amount depending upon the strength of spring 41. Since the pressure in the chamber 45 is substantially the same as that on the upstream side of the jet system 31, it may be seen that the pressure differential between chambers 5| and 56 of the pressure meter 22 is a measure of the pressure differential across the jet system 31, and hence is a measure of the quantity of fuel flowing to the engine, for any given position of the mixture control 34 and the valves 61 and 68.

This pressure differential between chambers 5| and 56 acts on the sleeve valve 51 in an opening direction, while the pressure differential between chambers 2| and 24, which, as previously described, is a measure of the mass of air entering the carburetor, acts on sleeve valve 51 in a closing direction. The movement of valve 51 in the closing direction causes an increase in the pressure in chamber 5|, and is transmitted thru conduit 50 to chamber 44, where it causes an opening movement of valve 46 and a corresponding increase in pressure on the upstream side of the jet system 31. Likewise an opening movement of sleeve valve 51 reduces the pressure in the chamber 5|, which reduction is transmitted to fuel regulator 32 where it causes a reduction in the pressure on the upstream side of the jet system 31 and hence a reduction in the quantity of fuel flowing to the engine.

Changes in pressure in the chamber 83, which might be occasioned by variations in the pressure acting on the discharge nozzle, or by variations in the pressure in chamber 82, act thru the pressure meter 22 to produce corresponding changes in the pressure on the upstream side of the jet system 31, and hence have no effect on the quantity of fuel entering the engine. For example, an increase in pressure in chamber 83 is transmitted thru conduit 81 to chamber 56 of pressure meter 22, where it operates to move sleeve valve 51 toward closed position thereby increasing the pressure in chamber 5|, which increase is transmitted thru conduit 50 to chamber 44, where it operates to open valve 46 and provide a parallel increase in pressure on the upstream side of jet system 31. The pressure differential across the jet system I31 therefore remains unchanged by the variation in pressure in chamber 83, and the quantity of fuel flowing thru the jet system 31 likewise remains unchanged.

When the throttle is in the idle range, the pressure differential produced by the low air flow is so small that its effect on the pressure meter 22 is erratic and unpredictable. Therefore, provision is made at such times to transfer the control of the fuel flow from the pressure meter 22 to the idlev valve 88. This is done by the spring 41 which tends to move the valve 46 toward open position. When the air pressure differential acting on diaphragm 54 is small, the valve 51 opens wide, reducing the pressure in chamber 5| of pressure meter 22 and in chamber 44 of fuel regulator 32. Spring 41 is then effective to open Valve '45 so as to cause a flow of fuel substantially greater than that required to balance the pressure in chamber 44. This flow is reduced in proportion to the position of throttle |4 by the idle valve 88, which is connected to throttle I4, as previously described.

When the valve 62 of mixture control 34 is in the position shown in full lines in the drawing, and the valves 81 and 68 are closed, fuel flows to the engine only thru the xed restriction 64. Under these conditions, a very lean mixture of fuel and air is supplied to the engine. As the load on the engine increases, the pressure differential across the jet system 31 is increased, and when it exceeds a value determined by the strength of spring 1|, the valve 68 opens, thereby allowing additional fuel to flow thru restriction 66, and enriching the mixture of fuel and air. In a similar manner, the valve 61 is opened when the pressure differential across the jet system eX- ceeds a Value determined by the strength of spring 1U. The springs 18 and 1| are preferably so chosen that the valve 68 opens at a lower value of differential pressure across the jet system than does the valve $1. The position of valve 62 shown in the drawing may be termed the special lean or emergency lean position of the mixture control 34.

When the disc valve 62 is rotated to the position indicated by the dotted line 49 in the drawing, the cam 'i5 is rotated so as to force the valve 68 open. The fuel and air mixture is thereby enriched by the same amount that would occur if the fuel differential pressure had increased above the value determined by the strength of spring 1|. This position of valve 62 may be termed the lean or normal lean position of the mixture control 34.

When the disc valve 62 is in the position indicated by the dotted line 59 in the drawing, fuel flows thru both conduits 35 and 36 to the jet system 31, and the valve 68 is still held open by the cam 15. This position may be termed the rich position of the mixture control 34.

When the throttle I4 is in its idle range, the cam 16 operates valve 58 to open position, thereby increasing the fuel to air ratio and insuring the operation of the engine under idling conditions With at least a normal lean mixture.

The variation of the fuel to air ratio with varying air flow in the various positions of the mixture control 34 is graphically illustrated in Figure 3. When the mixture control is in the special lean position shown in full lines in the drawing, the relationship between the fuel and air ratio and the air flow is illustrated by the curve A in full lines in Figure 3. In the range from zero air flow to the point 92 in Figure 3, the valve 58 is held open by the cam 16 so that the fuel to air ratio varies thru an intermediate range of values. When the air ow increases above that indicated by the point 92 in Figure 3, the cam 16 allows valve 68 to be closed by spring 1|, thereby decreasing the fuel to air ratio, which then varies in accordance with the full line between the points 92 and 93. air flow increases to the valuev indicated by the point 93, the fuel pressure differential increases sufciently to open valve 68 against the spring 1|, so that the fuel to air ratio has an intermediate range of values. The spring 18 is arranged so that valve 61 opens at a value of air flow indicated by the point 94 in Figure 3, and the fuel to air ratio is thereby further increased when.

When the f When the disc valve |52A is in the normal lea-ni" position illustrated by the dotted line 49f1in Figure l, the relationship between the fuel and air ratio and the air flow mostly follows the curve A in Figure 3, except that it follows the dotted lineV between the points 92 and 93, since under these conditions the valve S8 is open at all air flows.

When the-disc valve 62 is in the rich position indicated by the dotted line- 59, the relationship between fuel and air ratio and air flow is that illustrated by the curve B. in Figure 3.

Figure 2 There is shown in Figure 2 an ignition timing control system which may beusedwith the mixture control system of Figure 1 in order to advance the ignition timing whenever a very lean fuel and air mixture is supplied to the engine.V

Referring to Figure 2, there is shown an arm attached to a shaft |02 which operates suitable ignition timing control mechanism, which may be of any desirable type. Bracket |03 is attached to the center of the arm` |0|. A rod |04 passes freely thru an aperture in the bracket |Il3 On the right hand side of bracket |03, the rod |04 carries a washer |05 which prevents the rod |04 from passing thru the aperture in the bracket |03 and permits the movement ofv arm |0| in a counter-clockwise direction by the rodY |04.

rEhe movements of arm lill are limited by a pair of stops |06 and |01'. A spring |08 biases the arm |0| for movement against the stop |01. 'Ihe ignition timing control mechanism operated by shaft |02 is so arranged that the ignition timing; is normal when the arm |i| is against stop |00., and is advanced when arm |0| is against stop The movements of rod |04 arecontrolled bya differential pressure responsive operating mech;- anism generally indicated at ||0. This mechanism includes a housing separated by exible diaphragm ||2 into a pair of expansible chambers H3 and H4. The chamber H3 is connected to the conduit 25 of Figure l and the chamber ||4 is connected to the conduit 20 of Figure" I, so that the diaphragm l2 is operated by a pressure differential which is a measure of the quantity of air entering the engine. The diaphragmV ||2 is biased for movement toward the right by a spring l l5. A sealing diaphragm i0 closes the opening in the casing thru which the rod |04 passes.

From the foregoing, it may be seen that. when the pressure differential acting on the diaphragm ||2 is suiliciently high to overcome the springs |98 and ||5, the arm |0| is operated to the full', line position, in which position the ignition timing is normal. When the pressure differential acting on diaphragm ||2 is less than this value, the springs |98 and ||5 cooperate to move the'- arm |0| in a direction to advance the ignition timing. The springs |08 and I|5 are preferably chosen so that the ignition timing is advanced. whenever the air now is less than that corre` spending` to the point 93 in Figure 3.

An elongated link |29 is pivotally attached to the upper end of arm |0|. The opposite end of the link |20 passes freely thru an aperture in a pin |2I, which is rotatably and slidably mounted in a slot |22 in an arm |23 attached tor the throttle shaft |00. When the arm |23 is in the position shown in full lines in Figure 2, the throttle is in its closed position. As the throttle is movedl toward open' position, the arm"|`23 is moved to ther-ight.A The |"2-0 has a plate |24 fixed-- on it, so as to limit its sliding'movement thru thepin |2F. The pin |f21| andvsiot |22, eooperating with theplate |24- on link |20, provide a lost motion connection by which the throttle shaft may be operated toward open position without changingthe positionA of link-V |20. When thethrottleis moved toward closediV position, however, the pin |-2| engages pla-te |24 and positivelyp moves link |26 to the left, thereby moving arm |0| against-'thefstop |06- to establish normar ignition timing. The arrangement is preferably such thatl the arm |'0-f is operated to its normal timing rposition at'A the samel throttle position that cam` N5v operates valve G0' to open position. l

Near its center, the link` |20 passes thru a pin |25 rotatably mounted in the end of anv arm |26 attached to the. mixture control shaftv 631. A spring retainer' |21 is attached. to thepin F25 and another spring retainer |28 is xed on the link |23. The retainers |21 and |28 retain between them a compression spring |30, which is stronger than the spring |08 which urges thearm' |0| to its advanced timing position.

When the disc valve 62 isin the rich position indicated by the dotted line 9|. in Figure 1, the arm |23, is in the position shown in full lines in Figure 2. The spring |30 then overcomes the spring |08 and causes theA arm |0| to be moved' against stop |06.

When the mixture control 34. is moved sothat the disc valve 62 assumes the position indicated by the dotted line4 99 in Figure 1,. the arm |26. isV

moved somewhat to the right from the position illustrated in full lines but` not as far as the dotted line position in Figure 2'. Under such conditions, the spring |30 is extended somewhat. but still overcomes the spring |08 andA retains the link |20V and arm |0|' in the normal ignition timing position.

When the. mixture control34. is operated so that the valve 62 moves to the position. indicated by the full line in Figure 1, the arm |261 moves to the position shown, in dotted lines in Figure 2. Under those conditions,.the spring [30 isno longer effective to overcome the spring |08, andthe latter moves arm |0| to the advanced ignition timing position From the foregoing, it may be seen that when the. mixture control 34 is operated. to, select. the rich fuel and air ratio illustrated by the curve. B

in Figure 3, the ignition timing control is oper-- ated to give normal timing.. Likewise, when the mixture. control is operated to. produce the nor-V ows less than that correspondingto point. 92 of Y Figure 3, and the mechanism |.0 operates to. in.-

sure normal ignition timing at air flows. higherf than that corresponding to the point 93. of Figure 3- At air flows in the range. between the points 92 and 93 of Figure 3, the ignition.timing.isad.`Y

vanced by the spring |08.

Figure 4v There is illustrated in Figure 4 a modified form of mixture control and jet system which may be used in place of the mixture control 34 and jet system 31 of Figure 1. In the mixture control of Figure 4, it is not necessary to use mechanical connections for positively opening a valve in the jet system in accordance with the positions of the mixture control and throttle, such as the cams 15 and 16 in Figure 1.

In Figure 4, the fuel ows from the conduit 33, which may be the same as the conduit 33 of Figure 1, thru a mixture control |40 and a jet system |4| to a conduit 38, which may be the same as the conduit 38 of Figure 1. The mixture control |40 includes a disc valve |42 fixed on a shaft |43, which is rotatable to open and close ports connected with the conduit 33 and with conduits |44 and |45 thru which fuel may iiow from the mixture control |40 to the jet system |4|. The jets or restrictions 64, 65, 11 and 18 and their related parts are the same as the corresponding elements of Figure 1. In the jet system of Figure 4, the restriction 66v and the valve 68 of Figure 1 have been replaced by a restriction |46 thru which the fuel ow is controlled by a valve |41 operated by a flexible diaphragm |48. The diaphragm 48 is enclosed in a housing |50, which it separates into a pair of expansible chambers and |52. The chamber |5| is connected by a conduit |53 to the conduit |45, andthe chamber |52 is connected by conduit |54 to the conduit |44.

The valve |41 is of the piston type and moves in a cylinder |55 provided with a port 56 opening near its center. The piston valve |41 is biased downwardly by a spring |51 and is provided with apertures |58 to permit fuel to flow readily to both ends of the piston, thereby preventing dashpot action. It will be seen that when the piston valve |41 is in the position illustrated in the drawing, the port |56 is closed, and no fuel can then pass thru the restriction |46. As the piston valve 41 moves in either direction from its central position, the port |56 is uncovered, thereby permitting the flow of fuel thru the restriction Operation of Figure 4.

When the mixture control |40 is in the position shown in the drawing, which may be termed its lean position, fuel flows only thru the conduit |44, and the pressure in chamberv l 52 is the same as that on the upstream side of the jet system, while the pressure in chamber |5| is the same as that on the downstream side of the Ajet system.

The latter pressure is conveyed to the chamber |5| thru the restrictions 18 and 11 and conduits |45 and |53. Since there is then no fuel flowing thru the jets 11 and 18, there is no pressure drop across them. Therefore, when the mixture control |40 is in the position shown in the drawing, the position of valve |41 is controlled 'by the pressure drop across the jet system, which is in turn controlled by the quantity of air flowing thru the carburetor. biased downwardly by the spring |51, it may be seen that when the air flow is low, the valve |41 is moved downwardly so as to open the port and permit fuel to fiow thru restriction |46. At such times, the,relationship'between the fuel and air ratio and the air flow is that illustrated by the curve A in full lines in Figure`3. As the air flow increases, a value is reached which is determined by the strength of spring |51 and which may Since the valve |41 is' l0 preferably correspond tothe point 9'2 of Figure 3. When this value is reached, the pressure differential across the jet system compresses the spring |51 sufciently to move the valve |41 so as to close port |56, thereby decreaseing the fuel to air ratio. As the air ow continues to increase, the fuel and air ratio remains at a low value until the pressure differential across the jet has increased sufficiently to move the diaphragm |48 and valve |41 upwardly far enough to open the port |56 again. This may occur at an air flow corresponding to the point 93 ofA Figure 3.

When the mixture control |40 is moved to a position wherein fuel Hows thru both the conduits |44 and |45, which may be termed its richf position, the pressures in the chambers |5| and |52 are equal, and the valve 41 is then moved' downwardly by the spring |51 to open the port |56 and permit fuel to fiow thru restriction |46. It may therefore be seen that the mixture control system of Figure 4 is functionally the same` as that of Figure 1, except that no intermediate position of the mixture control is provided where the pilot may select a relationship between the fuel to air ratio and the air flow corresponding to the dotted line in Figure 3.

Figure 5 There is shown in Figure 5 a modified form ofy mixture control and ignition control mechanismwhich may be used to replace the mixture control of Figure 1 and the ignition control of Figure 2.

In the system shown in Figure 5, no mechanical connections between the Amixture control, the throttle and a valve in the jet system are necessary, and furthermore the fuel pressure is utilized as a source of power to operate the ignition control device.

Referring now to Figure 5,4 there is shown a mixture control |60 which receives fuel from 'a conduit 33, which may be the same as conduit 33 of Figure 1, and discharges it thru one or more of the conduits |6|, |62 and |63 to a jet system generally indicatedv at |64, whence the fuel iiows to a conduit 38, which may be the same' as the-` conduit 38 of Figure 1;

The mixture control |60 includes a disc valve" |64 fixed on a shaft |65 rotatable by a suitable mixture control Alever operated by the pilot. The 1 valve |64 controls the flow of fuel thru portsconnected to the conduits33, |6|, |62-fand 163.

The jet system |64 includes jets 64, 65, 11 and- 18 which are the same as corresponding jets in Figure 1.

, is operated by a fluid motor |16 including a diaphragm chambers |18 and |80. The chamber |18 is connected to conduit |12, and the chamber is connected to conduit |15. The diaphragm |11 is biased upwardlyby a spring |8| and is attached at its center to a rod |82 connected with suitable In the jet system |64 of Figure 5,v there is also provided a valve |66 operated by av diaphragm |61 which separates two expansible 5, the ignition control` 11 separating `a pair of expansible.

encaisse Operation of Figure `When the mixturecontrol 6l) lis in the position illustratedin full lines, the pressures in chambers Hi8-and |10 are equal, since they .are connected thru restriction |13,-thruwhich no fuel is iiowing -at this time. The valve |66 is thereforeY moved to closed `position by spring |1I. The A,relationship between fuel to-air ratio and `air .now is lthen the relationship determined by the restrictions 64,- 65', 11 and `18, andrepresented by the curve B of Figure 3.'- At this time, the pressure in chamher-|811 is that existing Ourthe-upstream side of the jetvsystenn while the pressure in the chamber Vla-is that-existing onthe `downstream side of the jet system. The `pressure differential across the Y jet system therefore Aacts on theYdiaphragm-HJ to aid thespring V|8-| in maintaining the ignition control in its normal position.

If the mixture control HillV isnowoperated-to move the valve |64 from the ful-lV line position in the drawing tothe dotted line position, the flow of fuel thru conduit |62 is cut off While fuel is admitted to conduit 16|. TheV fullline position oft-he valve |64 is its frichr position and the dottedline position is .its Ylean2 position. Y

lWhen vthe mixture control is in its lean position;the pressure differential across the jet sysvtem is lapplied to the diaphragm |51, since the chamber |68 isconnected to thedownstream side of the jetsystem thru conduit Htl, andthe chamber |16 is connected -to the upstream` side .of the jetsystem thru conduit |6|. Under these con-V ditions, the relationship between the iueljand air ratio and the air riiowfollows the curve Cof Figure 3 luntil the value of airflow is reached where the fuel pressure dilerential becomes sufdcientto overcome spring |1| and openvalve |66. This fuel pressure differential may be obtained at anxair-flow corresponding to the .point 950i Figure 3. When the valve |66 is opened,lan 'additional amount cffuel flows thru Yjet 11,iand the fuel 'to air ratio then varies with the air 'flow according to a 'characteristic such Vas curve A Yof Figure 3.

- When thevalve |64 is in Yits vdotted line or lean position, the pressure in chamber V| 18 is the samen asthat of the upstream side of the jet system, to which it is connected thru'conduit |12, chambr`f|1|1 'and'conduit' IBI. The pressure in chamber |80 atthis time Visthe same asuthat on the downstream side of the jet system, to which it Yis connected thru conduit and restrictions' 11" and 18. Since no fuel is flowing thru restrictions 11 and 18 as long as valveV |66is closed, there is no pressure drop across them. Inthe fluid'motor |7176., the pressure dierential across the jet system is now vacting in opposition to the spring 13|. At low valuesof airflow, theignitionrtiming re-` mains normal, but vwhen a valuerof Vair flow is sures'in chambers |18 vand |80 are equalized thru VYthe valve llifand-th'eignition control is operated to its normal position by the uspring `|8 l.Y I

1-2 Y It will be readily recognized by those skilled in thea-rt that mechanism may be readily provided for-adjusting thetension of the `springs |31 and ift! of `Figure 5 `and the Aspring |51 lin Figure 4 so as to control the particular values of air flow at which the various ignition timing and mixture control operations Vtake place.

`While I have illustrated my invention as applied to a fuel supply system in which the fuel and air are mixed before entering the combustion chamber, it is equally applicable to a direct injection system wherein the fuel is supplied Y directly to the cylinder of the internal combustion engine. Y

Altho I have shown and described certain preferred embodiments-of my invention, other modincations thereofY will readily occur to those skilled Vin the art, and I therefore intend my invention to be limited only by theV appended claims.

I lclaim as my invention:

'1. Control'lapparatus for an internal combustion engine, comprising `movable means for controlling the ignition timing of said engine, a conduit for supplying air to said engine for combustion purposes, means associated with said conduit for producing two unequal pressures whose difference is indicative of the quantity of air lowing'therethru, means for varying the ratio of fuel to air suppliedto said engine including a manually operable Ymember movable between a rst position corresponding to a lean fuel to air ratio and asecond position corresponding to a .rich fuel to air ratio, means operated by the difference of said pressures formoving'said ignition timing control means, and means effective upon movement of said member to said second position to rcause operation of said ignition timing control means to establish normal ignition timing, regardless of the difference of said pressures.

2. Control apparatus for an internal combustion engine, comprising means for controlling the ignition timing of said engine, a conduit for supplying air to said engine for combustion purposes, means associated with 'said conduit for producing two unequal pressures whose difference is indicative of the quantity of air iiowing therethru, means for varying the ratio of fuel to air supplied to said engine including a manually operable member movable between a first position corresponding to a lean fuel to 'air ratio and a second position corresponding to a .rich 'fuel to air ratio, means responsive to the difference of said pressures for operating said ignition timing control means and a control element associated with said ignition timing control means, said control element being biased to a first position wherein said ignition timing control means is operated in accordance with said difference of pressures and movable to a second position wherein said ignition timing control means is operated to establish normal ignition timing, said member being eiective upon movement to its second position to operatively engage Ysaid control element and positively move it to its second position.

3. Control apparatus for an internal combustion engine, comprising a rst conduit for air flowing to said engine for combustion purposes, throttle means for controlling the ow of air thru said conduit, means for producing two unequal pressures whose diierence is indicative of the quantity of air owing thru said first conduit, a second conduit forrfuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential einseitigev across said metering restriction means and hence the quantity of fuel flowing therethru, first means for controlling the cross-sectional area of said restriction means to control the ratio of fuel to air supplied to said engine including a member movable between a first position corresponding to a lean fuel to air ratio and a second position corresponding to a rich fuel to air ratio, ignition timing control means, second means for additionally controlling the cross-sectional area of said restriction means, means responsive to said difference of pressures for operating said second means and said ignition timing control means, mechanical means operative as an incident to movement of said member to said second position to override said operating means and to move said second means to an area increasing position and said ignition timing control means to establish normal ignition timing, and mechanical means operative as an incident to movement of said throttle means into a range of positions near its closed position to override said operating means and to move said second means to an area increasing position and said ignition timing control means to establish normal ignition timing.

4. Control apparatus for an internal combustion engine, comprising a first conduit for air flowing to said engine for combustion purposes, means for producing two unequal pressures whose difference is a measure of the quantity of air fiowing thru said first conduit,v a second conduit for fuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restriction means and hence the quantity of fuel flowing therethru, means for controlling the crosssectional area of said restriction means to control the ratio of fuel to air supplied to said engine including a member movable between a rst position corresponding to a lean fuel to air ratio and a second position corresponding to a rich fuel to air ratio, ignition timing control means, means responsive to said difference of pressures for operating said ignition timing control means, and mechanical means operative as an incident to movement of said member to said second position to override said operating means and to move said ignition timing control means to establish normal ignition timing.

5. Control apparatus for aninternal combustion engine, comprising a first conduit for air flowing to said engine for combustion purposes, throttle means for controlling the flow of air thru said conduit, means for producing two unequal pressures whose difference is a measure of the quantity of air flowing thru said rst conduit, a second conduit for fuel flowing to said engine, means responsive to said difference of pressures for controlling the quantity of fuel flowing thru said second conduit, ignition timing control means, means responsive to said difference of pressures for operating said ignition'timing control means, and mechanical means operative as an incident to movement of said throttle means into a range of positions near its closed position to override said operating means and to move said ignition timing control means to establish normal ignition timing.

6. In a carburetor for an internal combustion engine, in combination, a main conduit for the fuel flowing thru said carburetor and a pair of parallel branch conduits, each said branch conduit having a restriction therein, mixture control valve means for selectively permitting the flow of fuel thru one or both of said branch conduits, fuel flow controlling means for varying the fuel flow thru said main conduit and hence the pressure differential across said restrictions, a third branch conduit including a restriction and connected in parallel with the restriction in said one branch conduit, a single valve for controlling the flow thru said third branch conduit, a valve port closed by said valve in an intermediate range of positions thereof and opened when said valve is outside said range in either direction, and means for operating said valve in response to the difference between the pressure differentials across the restrictions in said pair of conduits.

' 7. Control apparatus for an internal combustion engine, comprising a first conduit for air flowing to said engine for combustion purposes, means for producing two unequal pressures whose difference is a measure of the quantity of air flowing thru said first conduit, a second conduit for fuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said restriction means and hence the quantity of fuel flowing therethru, means including g, valve for controlling the effective cross-sectional area of said restriction means to control the ratio of fuel to air supplied to said engine, a pair of expansible chambers separated by a movable wall, a first passage connecting one of said chambers to said second conduit at a point upstream from Said restriction means, a second passage connecting the other of said chambers to said second conduit at a point downstream from said restriction means, means including said wall for operating said valve, ignition timing control means including a movable member, means biasing said member to a position in which said control means establishes normal ignition timing, and means subject to the pressure differential across said valve to operate said ignition timing means against said biasing means, said biasing means being effective Whenever said valve is open to cause establishment of normal ignition timing.

8. Control apparatus for an internal combustion engine, comprising a first conduit for air owing to said engine for combustion purposes, means for producing two unequal pressures whose difference is a measure of the quantity of air flowing thru said first conduit, a second conduit for fuel flowing to said engine including at least two branch conduits, metering restriction means in said branch conduits, means responsive to said difference of pressures for controlling the pressure differential across said restriction means and hence the quantity of fuel iiowing therethru, mixture control means for selectively controlling the number of said branch conduits open to the flow of fuel to control the ratio of fuel to air supplied to said engine, said mixture control means including a member movable between a first position corresponding to a lean fuel to air ratio and a second position corresponding to a. rich fuel to air ratio, means including a valve in one of said branch conduits for additionally controlling the fuel to air ratio, a pair of expansible chambers separated by a movable wall, means including said wall for operating said valve, means biasing said valve to closed position, means including certain of said branch conduits for connecting said chambers to the opposite sides of said restriction means so that the pressure differential thereacross acts in opposition to said biasing means,

ignition timing control means including a mov-v able elementnreans biasingsaid-element to-'a poi sition in which saidn control means establishes normal `ignition timing, means responsive to the pressure diierential across said valve to `operate said Vignition timing means against its biasing means, said last-named biasing means being effective whenever said valve is open to cause establishment of normal ignition timing, and means operative as an incident to movement of said member to said second position to selectively close and'open said branch Vconduits so as to apply the .pressure 'differential across said restriction means to `said ignition timing operating means in a direction to aid its associated biasing means.

'9. Control apparatus for an internal combustion engine, comprising a `fdrst conduit for air owing to said engine for combustion purposes, means for producing two unequal pressures whose diierence is a measure of the quantity `of vair flowing thru Asaid rst conduit, a second conduit for fuel owing to said engine, metering restriction Vmeans in said second conduit, means responsive to Vsaid difference vof pressures for controlling the pressure'differential across said metering restriction means andihence the quantity of fuel flowing therethru, means for controlling the cross-sectional area of `said Vrestriction means to control Athe ratio of fuelV to air supplied to said engine including a member movable between `a rst position corresponding to a lean fuel to `air ratio and -a second position corresponding to a rich fuel to air ratio, ignition timing control means, a pair of expansible chambers separated by -a movable wall, means including said wall lfor operating said ignition timing control means, fluid connections for supplying said pressure differential to said chambers for operating said ignition timing control means, and means operative as an incident to movement of said member from said flrst -to second positions t0 reverse said connections, said connections and said connection reversing means cooperating so that said pressure differential acts on said wall in ka direction to advance said ignition timing when said member is in said rst position and in a direction to retard said ignition timing when said member is in said second position. Y

10. Control apparatus for an internal combustion engine, comprising a iirst conduit for air nowing to said engine for combustion purposes, means for producing two Vunequal pressures whose Vdifference is a measure of the quantity of air flowing thru said rst conduit, a second conduit for fuel owing to said engine, metering restriction means in `said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restriction means and hence the Vquantity of fuel flowing therethru, means for controllingV Yby a movable Wall, means including said wall for operating said ignition timing control means, restricted uid passages connecting each of said chambers with saidfuel conduit downstream from said restriction means Yand means operative as Yan incident to movement of said member to' selectively'apply the pressure on the upstream side of said restriction means to one or the other Vof saidV chambersf'said passages and said last-named mesma means cooperating so thatsaid pressuredifferential acts on said'wall inadirection to advance 'said ignition timing when said member is in 'said -i'lrst position and in a direction to retard said ignition timing when said member `is in said second.

position.

11. Control apparatus 'for an internal combustion engine, comprising a i'lrst conduit for air owing to said yengine for "combustion purposes, means for producing two unequal Ipressures whose diierence is :a measure of the 'quantity of air flowing thru said rst conduit, a second conduit for fuel owing to said engine, metering restriction means in said second conduit, means respon'sive vto said difference ofupressures for controlling the pressure 'diierenti'al across said metering restriction means and 'hence'the quantity of fuel flowing therethru, means for controlling the cross-sectional area'of 'said restriction means to control the ratio vof fuel to air supplied to said engine including a member movable between la first position corresponding to 'a lean fuel to air ratio and fa'second position corresponding'to a richvfuel to iair ratio, ignition timing control means, a pair of eXpansible chambers separated by 'a' movable wall, means including said wall for voperating 'said ignition timing control means, uid `connections for .supplying said pressure differential Vto Ysaid chambers for operating said ignition timing control means, means operative as an incident 'to movement of said member from said rst to second positions to reverse said connections, said connections `and said connection reversing means lcooperating so -that said pressure diierential Aacts onV said Vwall in a direction to advance said ignition timing when said member isin said first position and in -a 'direction to retard said ignition ltiming when said member is in said second position, means biasing said ignition timing control means "to a nprmal position, and means effective when` said member -is in said rst position and Ysaid pressure differential exceeds a predetermined value to establish a iiuid connection between said ychambers :so Lthat said ignition timing control means is operated to said normal position by said biasingmeans.

12. Control apparatus for van internal combustion engine, comprising a 'first yconduit lfor air iiowing to said engine .for combustion purposes,`

means for producing two unequal pressures whose difference is a measure of the quantity of lair flowing thru :said first conduit, a second conduit lfor fuel ,flowing to 'said engine, ignition timing control means including a movable element, means biasing said element to a position in which said ignition timing is advanced, means responsive to said difference of pressures for operating said ignition timing 'control means to retard said ignition timing when said difference exceeds a predetermined val-ue, mixture control means including a member 'movable between a first position corresponding toa lean fuel to air ratio andra second Vposition corresponding to va rich fuel to air ratio, vand means Yoperative as an incident to movement Aof said 'member to said second position to operate 'sai-d ignition timing control means to retard said .ignition timing.

13. Control apparatus Afor an internal combustion engine, comprising a nrst conduit for air flowing to said engine for combustion purposes, means for 'producing two unequal pressures whose difference is a measure 'of the mass ofair flowing thru said first yconduit per unit time, a second conduit for fuel nowing V'to lsaid engine, metering restriction meansfin 'said second conduit, means :incassa 17 responsive to said difference of pressures for controlling the pressure differential across said metering restriction means vand hence the quantity of fuel flowing therethru, means for controlling the cross-sectional area of lsaid restriction means to control the ratio of fuel-to-air supplied to said engine including a member movable ibetween the first position corresponding to a lean fuel-to-air ratio and a second position corresponding to a rich fuel-to-air ratio, ignition timing control means movable between a normal timing position and an advanced timing position, a first control element movable between a first position and Ia second position, means biasing said element to said rst position, a diaphragm responsive to said difference of pressures for moving said element to said second position when said difference exceeds a predetermined' value, a second control element movable lbetween a first position and a second position, means biasing said second element t its rst position, means associated with said member lfor moving said second element to its 'second Iposition as said member moves from its rst to its second positions, and means including said elements for controlling the movements of said ignition timing control means to move said ignition timing control means to its normal timing position when either of said elements is moved to its second position.

14. Control apparatus for an internal combustion engine, comprising .a rst conduit for air ilowing to -said engine for combustion purposes, throttle means for controlling the now of air thru said conduit, means for producing two unequal pressures whose difference is ya measure of the mass vof air flowing thru said rst conduit per unit time, a second conduit Ifor fuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restriction means and hence the quantity of fuel flowing therethru, ignition timing control means movable between a normal timing position and an advanced timing position, a rst control element movable between a first position and a second position, means biasing said element to said first position, a diaphragm responsive to said difference of pressures for moving said element to said second position when said difference exceeds a predetermined value, a second control element movable between a rst position and a second position, means biasing said second element to its first position, means associated with said throttle means for moving said second element to its second position as said throttle means moves into a range of positions `adjacent its closed position, and means including said elements for controlling the movements of said ignition timing control means to move said ignition timing control means to its normal timing position when either of said elements is moved to its second lposition.

15. Control apparatus for an internal combustion engine, comprising a first conduit for air flowing to said engine for combustion purposes, means for producing two unequal pressures whose difference is a measure of the quantity of air flowing thru said rst conduit, a second conduit for fuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure diiferential across said metering restriction means and hence the quantity of fuel flowing therethru, means for controlling the cross-sectional area of said restriction means to control the ratio of fuel-to-air supplied to said engine, including a member movable between the rst position corresponding to a lean fuel-to-air ratio and a second position corresponding to a rich fuel-to-air ratio, ignition timing control means movable between a normal timing position and an advanced timing position, a control element movable between a first position and a second position, means biasing said element to its first position, means associated with said member for mechanically engaging said elemeni-l to move it to its second position as said member moves from its rst to its second positions, and means including said element for controlling the movements oi said ignition timing control means to move said ignition timing control means to its normal timing position when said element is moved to its second position.

16. Control apparatus for an internal combustion engine, comprising a rst conduit for air flowing to said engine for combustion purposes, means for producing two unequal pressures whose difference is a measure of the mass of air owing thru said rst conduit per unit time, a second conduit for fuel owing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restriction means and hence the quantity of fuel flowing therethru, ignition timing control means movable between a normal timing position and an advanced timing position, a rst control element movable between a first position and a second position, means biasing said element to said first position, a diaphragm responsive to said difference of pressures for moving said element to said second position when said difference exceeds a predetermined value, a second control element movable between a first position and a second position, means biasing said second element t0 its first position, means responsive to a condition indicative of the need for establishment of normal ignition timing for moving said second element to its second position when said condition assumes a predetermined value, and means including said elements for controlling the movements of said ignition timing control means to move said ignition timing control means to its normal timing position when either of said elements is moved to its second position.

17. Control apparatus for an internal combustion engine, comprising a first conduit for air flowing to said enginefor combustion purposes, throttle means for controlling the flow of air thru said conduit, means for producing two unequal pressures whose difference is indicative of the quantity of air flowing thru said rst conduit, a second conduit for fuel flowing to said engine, metering restriction means in said second conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restriction means and hence the quantity of fuel flowing therethru, means for controlling the cross-sectional area of 'said restriction means to control the ratio of fuelto-air supplied to said engine including a member movable between a lirst position corresponding to a lean fuel-to-air ratio and a second position corresponding to a rich fuel-to-air ratio, ignition timing control means, means responsive to said difference of pressures for operating said ignition timing control means, first mechanical means operative as an incident to movement of said member to said second position to override said operating means and tomove said ignition timing control neansftofefstablish vnormal ignition timing, and .second/fmechani'cal means operative as an incident to ino ornent/fof said throttle means into arangefof positionsadjacentits closed position to override Said operating means vand to move 'said ignition timing lcontrol means to establish normal ignitintimin'g.

Y 18. Control apparatusfran internalcornbustion engine, comprising `afiirs't conduit for air owing to said eiigineior combustion purposes, nieaiis'for producing t'wo unequal pressures whose difference is a measure of. the'inass of air nowingthrusaidiirst conduit kper unit time, a second conduit'for, fuel flowing'to said engine, at least three iparallel 'In'tfr'g "'trctions in Said Secorio lconduit, responsive to said difference of pressuresior cotrolli'g'the pressure differential across said meterg're'strictions'andyhence the quahtityfvful'owffgdthethrl, means for controllin'g'tliettal crosssec'tinal area "of said restrictions 'to 'control `vthe ratio of fuel-,to-air supplied to .said ehgineir'icliiding a selector valve movable between. Ya `rst p'osition wherein fuel xnfay` ow th'r'u" two "of" saidf three restrictions 'and a"soooiiriV positionwii' fe'rifiiei'may 'now thru au ofsaid Athree rest'r tions, a single additional valveffor' co'rtrc'illing "neo'saidtwoV restrictions, operating mearsfor) 1d ditional Valve to open said additional ifalvewhe' isinitsifirstpositonia d ad'inass air flow is 'above or, below p're mined 'intermediate range 'ofvaljiesor y'l/,VlieneverVsaid selctorvali'le isVV in 'itssec'on'd position, "nition'timing Acontrol .means movableV betwefnfa 'nolrlnal vtiming position and anadvanc'ed timirgjpsitionfa :first control element niovablebetween af'first 'positionand a second p'ositi`on, nieansbiasing said element vto said frS'f position, a'diaphralnfresponsive to said difference of; pressures j for 'moving said element tosaidsecond position en s'aid difference exceedsa predeterminedwvaluega Vsecond control element n iovable` loeijltlleeii-v arst position and a second position, means biasingsaid second element to itsiirst'poS'itw' means"associatdfwith said 'selector-'valve for moving saidjsecond element to itsseoomifposition as aijrseiootor vaive moves rroinitslnrst toit soooriopositions, and' mesas includingsaid 'elements'f 4for' controlling the movements'of saidign on 'tiingfcontrol 'means'to move said ignit tion engine, comprising a'hrstcontiuit for air flowing; tol saidingine,fori'combiistion purposes, throttle' frrioans forooritroiii'rig tno now of air thru cond Itfm'ea'ns for producing two unequal pressures osedi'ierence'isa measure of the mass ofja-ir owinggthrdsaid first conduit per unit time, va second conduit for fuel yflowing to said; enginafatleast threei'parallel' metering restrictions-'insaid secondi' conduit," ineans' responsiveftosaid diflerericeyofA pressuresfor controlling thepressure dii'erentialiacross 'said 'metering vreotriotio'ris 'anrij hence trio quantity of `fuoifiowins therethru,VY means `vfor' controlling the' total' crosssectional areal o fj'sa'id restrictions' 'to control" the ratioof fuel-toiair fst'iplrli'edi''to said 'engine including ai selector'valve' movablebetween a -irst position wherein fii'oiin "*riow thruj two `orsaioi three' restrictions land a' Vs'ejc'ori'd position 'wherein fuor-'moynow thrujairof saidthroo restrictions, a single additional 'valve lfor *'ooitroiiing' on'eof nevesaid selector valve saidtwo restrictions, .means Xbiasing said additional valve-'towardclosed position, said additional valve being constructed so-as to open .in the vdirection oi fuel-flowln respon-setto an Vincrease rin said fuel pressure .differential above .a predetermined value, `first cam means vmovable concurrently withsaid selector valve for opening said additional valve .when said .selector -valve .is moved to itss'econdposition, and second cam means .movable concurrently with said throttle means for y.opening .said .additional Valve when said throttle means moves into arange of Spositionsadjacen-t its closed position. Y ,y 2U. Controlapparatus'for ani'nternal combustion engine, comprising a 'rst conduit `for air 'owirigto said .engine for .combustion purposes, means .for producing two unequal .pressures whose ldifference isia measure of the mass of air y flowing i thrusai'd iirst conduit per unit time, a-s`econd conduit fior, fuel flowing to said engine, atlleastfthree Iparalle'l.branc'li conduits connected to s a-idsecond condu'tpeac'h said branch conduit including a metering restriction, :means responsive to said'diferenceoffprssuresfor controlling the-pressure difierentialacross .said metering restrictions and hencethe quantity of 'fuel flowing therethru, `means for controllingfthetotal crosssectional area of .said restrict-ions tofc'o'ntrol the ratio of fuel-toair .suppliedfto said engine including a selector 'valve AmovableA betweena iirst position :wherein fuel may iiowthru two of said three -branch conduits and 'a ysecond `'position wherein [fuel vmay "flowfthru all of said three branch conduits, va single additional valve lior ooritroiiioggthe .now th'ruorio of said two branch conduits,a Valve port'closed by said valve in an intermediate frange of .positions thereof and opened when said valire'is'outs'de said rangein either'directiomf-apair of expansible chambers separated by a diaphragm, an operating connection between-'said diaphragm and said valve, meansV-biasing-said valveior movementto one end-oi its lrange, and-means connecting said chambers to-one, ofsai'd twobranch conduitsan'd thethirdfoivsaid -branolfrV conduits, respectively., at points between vthe-selector valvea-nd the restrictionin -saidrespectiveconduits, sol that the pressures in-said chambers `arefequal when said selectorl valveisfin-said second position andsaid biasing-means is' then'efiective toppen saidvalve. 21. l'Control' apparatus fora/n internal combustion 'engirieycomprisin'g a iirst vconduit for air owing "to 'saidf `engine for combustion i purposes, ineansfoit producing two unequal pressures Whose diierence *isindicativetof the quantity of -a-ir flowingi thru vsaidiirst conduit, a second conduit for- 'fuel flowing. to'said' "engine,metering restrictionf-inans ifn 'saidlsecondlconduiu ffmeans re- Sponsive' tof said difference"ofi-pressuresfor controlling '-the, pressure jidifferential across said metering restriction 'means Jan'd"hi'e'ncethe quantity lof fuel flowing therethru; means? forcontroilingthe cross-'sectional area of'said restriction means to control the ratio'of rfuel-to-air supplied to""said"engine including-a member movable'between a `firstr positionv lcorresponding to a lean fuelto-'air ratio and a second position corresponding to a rich fuel-to-air' rand-'ignition timing 4controlj r'rieans, means'responsive to said diference of'fpr'es'sures'for operatingjs'aid ignition timing controlfmeans, a control "element movable between a `first inactivejposition" and a" second"'posi tion wherein[it eiieotiv'ely interrupts' control' of said ignition" timing oontroi 'rrreansfoy` saidA 'pres'.

sure responsive means, means biasing said ele' three parallel metering restrictions in said sec-.

ond conduit, means responsive to said difference of pressures for controlling the pressure differential across said metering restrictions and hence the quantity of fuel owing therethru, means for controlling the total cross-sectional area of said restrictions to control the ratio of fuel-to-air supplied to said engine including selector valve mechanism movable between a first position wherein only a iirst of said restrictions is opened to the flow of fuel, a second position wherein said first restriction and a second restriction are opened and a third position wherein all of said restrictions are opened, and additional means for opening said second restriction to the flow of fuel when said selector valve mechanism is in its rst position and said mass air flow is above or below flowing thru said rst conduit per unit time, a'

second conduit for fuel flowing to said engine, at least three parallel metering restrictions in said second conduit, means responsive to said difference of pressures for controlling the pressure dierential across said metering restrictions and hence the quantity of fuel iiowing therethru, means for controlling the total cross-sectional area of said restrictions to control the ratio of fuel-to-air supplied to said engine including selector valve mechanism movable between a first position wherein only a first of said restrictions is opened tothe flow of fuel, a second position wherein said rst restriction and a second restriction are opened and a third position wherein all of said restrictions are opened, additional means for opening said second restriction to the flow of fuel when said selector valve mechanism is in its first position and said mass air flow is above or below Aa predetermined intermediate range of values, ignition timing control means movable between a normal timing position and an advanced timing position, and means associated with said selector valve mechanism to cause operation of said ignition timing control means to its normal timing position when said selector valve mechanism is moved to its second or third positions, and to permit opeiation of said ignition timing control means to its advanced timing position when said selector valve mechanism is moved to its rst position. y

24. Control apparatus for an internal combustion engine, comprising a conduit for supplying air to said engine for combustion purposes, means associated with said conduit for producing two unequal pressures whose difference is indicative of the rate of air fiow therethru, means for varying Atheratio of fuel to air supplied to said engine including a manually operable member movable between ,afirst position corresponding to a lean fuel-to-air ratio and a second position cor-f responding to a rich fuel-to-air ratio, a combus` tion control device associated with said engine" and movable between a first `position wherein ittends to oppose an excessive rise in the engine'A temperature and a second position wherein it increases the efciency of the engine, means biasing said control device to said second positionmeans responsive to the difference of said pres-I sures for operating said control device to said first position against said biasing means when said pressure difference exceeds a predetermined value, and a control element associated with said manually movable member for positively moving' said device to said first position regardless of said pressure diiference responsive means whenever said member is moved to its second position.

25. Control apparatus for an internal combus' tion engine, comprising a first conduit for air flowing to said engine for combustion purposes,

means for producing two unequal pressures whose difference is indicative of the rate of air ow thru said rst conduit, a second conduit for fuel flowing to said engine, metering restriction means inl said second conduit, means responsive to said difference of pressures for controlling the pressure` differential across said metering restrictioni means and hence the quantity of fuel flowing' therethru, means for controlling the cross-sec-'1 tional area of said restriction means to control the ratio of fuel-to-air supplied to said engine including a member movable between a first position correspondingV to a lean fuel-to-air ratio' land a second position corresponding to a rich l fuel-to-air ratio, a combustion control device as- 5 sociated with said engine and movable between 1 a rst position wherein it tends to opposeY an excessive rise in the engine temperature and a"l second position wherein it increases the efliciency of the engine, means biasing said control device to said second position, means responsive to the diiference of said pressures for operating said control device to said rst position against said biasing means when said pressure difference exceeds a predetermined value, a control element: movable between a first inactive position and a. second position wherein it effectively interruptsv control of said device by said pressure difference responsive means and positively holds said device in said rst position, and means operativeJ as an incident to movement of said membery to its second position to engage said control element and move it to its second position.

26'. Fluid dow control apparatus, comprising a'.

main fluid inlet conduit, a main fluid outlet conduit, a pair of parallel branch conduits each con# nected at one end to said inlet conduit and at the other end to said outlet conduit, a selector valve located at the junction of saidbranch conduits and open, at least one restriction in each of said branch conduits, a third branch conduit having its inlet end opening into said one branch con-- duit at the upstream side of the restriction therel in and having its outlet end opening into one of said conduits at a point where the pressure is substantially lower than that at the inlet end of said third branch conduit, a second valve in said: third branch conduit, and operating means for J said second valve, said operating means includ- 75. ing means to open said second valve concurrently 'withmcvement ,of :said selector waive .tofsaidseeondviposition .and means .to gmaintain-isaid; second valve :open :when said selector valve-is rin ,sardi rst position .and vthe Vpressure :drop -across @said second valve .is outsidexapredeterminedirangeof 5f.

values. v

..2-77. Fluid flowcontrol -apparatus,'comprising.ia main .uidfinlet conduitfamain uid-outlet-:.con duit, -.a pair of f parallel branch conduits :each

connected .at -one Vend .to .said inlet :conduit :and .10

at :the otherendv to'saidoutletrconduit a.;selec t0r valveJocated-at thejunction-.of said branchfconduits and` one -of :said main conduits, said selector ivalve ybeing movable between .fa rst iposit-ion wherein only. one` of said vbranch conduits gist open 15 and .a lsecond .position wherein .both said branch conduits Yare vopen, at least -one frestriction --in each .of -said branch conduits, va -third 1branch conduit. having `its vinlet .end opening .into-said one .branch .conduit Vat .the .upstream side of the 320 restriction .therein 4.and having its -putlet lend openinginto .one of Vsaid* conduits .atagpoint-where' thepressure is substantially lower -than .-:thatatthe .inlet end of. -said .third branch conduit;r a second valvein said .third branch conduit, andoperatingmeansor said .second valve, `said-riperatingineans being .eiective to-close said-second valve vwhen said selector .valve is 4in its first-pcf sitionand the pressure-dropacross saidvsecond valve is Within a predetermined Arange-of -values 30 and .to open.said;second Valveat .all` other -times.

2.8. I Fluid Vflow control ,.apparatus, comprising .a main.fluid in1et.condu'it,.a .main uidoutlet conduit. a.. pair of parallelv branch; conduits each .con-

nected v-at-.one end tofsaidinlet. conduit .and at :35

the other .end to .said outlet conduit, ia 4selector valve located. at lthejunction of saidbranch conduits .an'clone of said main.. conduits, said selector ,valve rbeing Vmovable ibetween ,a first position .wherein only onerof saidbranchfconduits .40

is. open and =afsecond position ywherein both.:said f branchconduits are open, at;least:onefrestriction in each of `said .branch lconduits, ca thirdlbranch con'duithaving vits .inlet .fend -opening -into lsaidV one'branchconduit at litheupstreamv side of the 1 restriction itherein vand'. having 'its outlet endopening into one of-said-conduits'at apoint where the pressure -is substantiallylower than that vat the inlet-endet' said third branch `conduitra-sec- 0 ond-valvein said third branch conduit, andfoper atingY means for said second Valve, said'operating means including aV spring Ybiasing said second valve toward closed position,` means responsivato thejpressure drop across ithe second valve for.,55

opening'it against thelbias of .said spring when said. pressure dropexceeds a rstpre'determined value, rst cam means. movableconcurrently with said selector .Valveior positivelvopening saidf second .valve when said selectorvalveis moved toV `6 its second .positionfand second. Cami-means operating ,under .a .conditiongenerally V.indicative of` the .pressure drop. across .said second ivalve -for openingsa'id Ysecond valve When-saidzcondition indicates .that said,l pressureV drop fhas fallen be.- lowfa second predetermined-,value lowerithanr said: rstlvalue.

29. .Fluid flow control apparatus, comprisingfaV main huid. inlet conduit, vaimain. luidloutlet conam duit, apair of; parallel branch conduitseach'connected at one .Y end to :said inlet conduit fand at. thefotheraend 1 to .said outlet.conduit,..a selector valveLlocatedflat the junction of saidbranchaconduits'anldlone of isa/id' main conduitsysaidsselector i155 valve .frbeing :movable rb etween n :.rst @position-vr whereinqonly .ione fof .said branch .(ilrnillllts*. is.v

open and :a second .position :wherein ":both [said:

branch conduits Pare fopen, :at least .one .frestric-' tion in each .of said ibranch conduits, a ithird branch conduit having its .inlet fendpopening into said one branch conduit .at the upstream' side kof the restriction therein and having :its

outlet-end opening iinto .one :of rsaidV 'conduits at fa point where :the pressure iis substantially` lower .than `ftha't .atfthe vinletend of `.said 'third branch conduit, a second valve and a :seatco-j operating therewith in saidv third branch con-y duit, said valve being effective whenl in an -intermediate range of positions `to rshut oil 'the flow thrusaidthird'branch rconduitgand .eiective upon movement in either directionA from saidintermediate range to permita flow of Huid thru .said

:th'ird'branch conduit, operating meansforaid` secondvalve including a pair of-expansible chambers. separated by .a movable v wall '..and a .connection .between said .wall Vand said :second eval-ve,

means-connecting saidchambers to said branchA .conduits at the 'upstreamsidesgof the restrictions: therein, a spring biasingsaidwallin Oppositionu tothe pressure in thelchambericonnected toxsaid:

one :branch conduit, saidispring.being'eiective'to Vsaid inlet and Aoutlet conduits is lbelow a first predetermined value, said movablewalljbeing i effective to cause opening of saidsecond valve by movement .thereof beyond, said intermediaterange inthe opposite direction vwhen said .selector valve is.. in. its :first -position and the pressure. difference between said inlet and outlet conduits excr-:edsV a second predetermined value higher than ...saidrst value.

.30. .l'luidr1lowzcontrol apparatus, comprisingfn ymainfluidinlet; conduit, .a mainflnid outletconduit, a pair .of parallel branch .conduits each connected atone .end to said inlet.` conduit vandat the other vend to said; outlet conduit, lla .se-

lector-Valve located at the junction of'said branch conduits and1one of saidV main conduits-said Aselector valve being movable between a "rst position wherein only one of` saidA` branch conduits is open and a second position wherein both said branch conduits. are open, at leastone restriction ineach of said branch conduits, a third .branch conduit having its inletendopening into said one-branch conduitat theupstream sideof the restricticnithereinfand havingv itsoutlet end open'- fing .into one :of f saidnconduitsgatiapoint where the pressurefis substantiallyrlower thansthat. at

the.` inlet. end.' ofsaidithirdr'branchtconduit;a second. valve infsa-id thirdbranchconduit;andmeans.; for operating-said ysecond valve, -said--'0perating l means beingA effective when vsaidselectorvalve -is in said rst position toppen said-second-va1ve whenithe pressurefdrop acrosssaid second'valve is above a ilrst predetermined value or'below a .isecond lower value andto close said .second valve when saidpressure drop is. between said irst and second values.

'SCOTT F.

`(References onrffollwing page) 25 REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Riege Sept. 11, 1923 Spiller Feb. 16, 1932 Harmon Aug. 31, 1937 Hunt Dec. 21, 1937 Worden Apr. 23, 1940 Udale Feb. 18, 1941 Weiche Sept. 28, 1943 Number Number OTHER REFERENCES Publication: Automotive Industries, June 15, 1941, pp. 620-624; vol. 84, No. 12. Copy in Patent Ofce Library. 

